  The concept of $\ell_{\Phi}$-decomposition, extending the concept of
$\ell_{p}$-decomposition of a Banach space, is presented and basic properties
of Schauder-Orlicz decompositions and $\ell_{\Phi}$-decompositions are studied.
We show that Schauder-Orlicz decompositions are orthogonal in a sense of
Grinblyum-James and Singer. Simple constructions of $\ell_{p}$-decompositions
and Schauder-Orlicz decompositions in $L_p$ are presented. We prove that in the
class of spaces possessing pseudo-Daugavet property, which includes classical
$L_p$, $1\leq p\neq 2$, and $C$, Schauder-Orlicz decompositions with at least
one finite dimensional subspace do not exist. It follows that Kato theorem on
similarity for sequences of projections [1] cannot be extended to spaces from
this class. Moreover we show that Banach spaces, possessing Schauder-Orlicz
decompositions with at least one finite dimensional subspace, do not have
pseudo-Daugavet property. Thus for Banach spaces $X$ possessing Schauder-Orlicz
decompositions we obtain the following characterization of pseudo-Daugavet
property: $X$ has pseudo-Daugavet property if and only if there is no
Schauder-Orlicz decomposition in $X$ with at least one finite dimensional
subspace if and only if there is no Schauder-Orlicz decomposition in $X$, which
is an FDD.
